FIG. 1 shows an example of such a truck 10 carrying a load 12. The truck has a U-shaped chassis 14 having a pair of arms 16, 18 extending forwardly of a bridge portion 20 with a fork lift mechanism 22 disposed between the arms. A pair of front wheels 24, 26 are disposed towards a front end 28 of the arms, one on either arm. A single rear wheel 30 is disposed centrally at the rear end 32 of the truck 10. In FIG. 1 the truck is shown with neutral steering in sideways mode.
Traditionally such trucks only drive with a single rear wheel 30. This can cause some undesirable effects when accelerating and braking. With a load on the truck, accelerating can cause the truck to torque steer around the load shown in FIG. 1.
The turning effect and direction is opposite but exaggerated during braking when only the rear wheel brakes. During braking the truck turns around the rear wheel due to the momentum of the load on top of the idle front wheels which have no braking. Due to the small wheel size the front wheels are idle and without brakes, they are a smaller diameter to keep the load platform low to maximise storage space. In this embodiment the rear wheel is larger than the front platform wheels for load carrying capacity.
FIG. 2 shows a truck that has one driven front wheel 26 and one driven rear wheel 30 using electric drive motors and brakes. The front right wheel 26 is driven and the front left wheel 24 idle. The turning effect is eliminated while accelerating, decelerating and braking with this solution. However the truck suffers from a problem when steering because the motor speeds and motor torque vary when turning left or right in either forward-reverse mode or sideways mode.
There is therefore a need for a load-carrying truck which addresses at least some of the drawsback of the prior art.